The Texas Rangers in collaboration with the Webb County Sheriff's Office are investigating the death of a woman whose body was found in the same vicinity where the body of another victim was found a week ago.

But both Alaniz and Cuellar declined to discuss the evidence or say how the women were killed.

Juan David Oritz has been charged over the murder of three women.

The third and fourth were found in the same area this weekend. The sheriff described the veteran Border Patrol agent as a "serial killer". Cuellar said investigators believe Ortiz acted alone.

On Thursday, 42-year-old Claudine Anne Luera was found fatally wounded off a roadway not far from where the previous body was found. Paramedics rushed the woman to a local hospital in critical condition. The names of the victims were not immediately released.

In a statement, Andrew Meehan, assistant commissioner for public affairs for U.S. Customs and Border Protection, said his agency's Office of Professional Responsibility, the U.S. Border Patrol and the Department of Homeland Security Office of the Inspector General are fully cooperating with all investigators.

"We want to reassure the citizens of Laredo that the community and your families are safe", the Laredo Police Department said in a statement on Saturday afternoon, according to the Houston Chronicle.